Terminal for electric discharge tubes



G- E. SHOEMAKE TERMINAL FOR ELECTRIC DISCHARGE TUBES INVENTOR: fieiazyeflslwemeg 2.1 (1

ATTORNEYS.

2 Sheets-Sheet 1 I iza Filed Jan. 14, 194g s. E. SHOEMAKER 2,4 9,999

TERMINAL FOR ELECTRIC- DISCHARGE MES Filed Jan. 14, me -2 Sheets-Sheet z.

INVENTOR:

' J 5 ATTORNEYS.

Patented Oct. 12, 1948 TERMINAL FOR ELECTRIC DISCHARGE TUBES George E. Shoemaker, Ithan, Pa.

Application January 14, 1948, Serial No. 2,187

This invention relates to electric discharge tubes and more particularly to terminals and fittings for supporting such tubes and carrying current thereto. Heretofore such tubes have customarily been provided with exposed contact members at their ends. As such tubes are frequently installed for operation in series in high voltage circuits it is desirable to reduce the hazard of electrical shock to a minimum.

The primary object of the present invention is to make possible the safe operation of hot and cold cathode tubes at relatively high voltages, and this end I accomplish by providing means for electrically connecting and mechanically supporting a tube in relation to a base having wires leading to a source of current supply, such means being so designed that no live part is accessible to human fingers.

Another object of the invention is to provide terminal fittings of the character referred to which are compact and inexpensive to manufac ture and consist of a minimum of parts and yet permit a tube to be readily and quickly connected to its supporting base or disconnected therefrom.

Another object of the invention is to provide terminal fittings of this character which are so designed as to allow for a substantial movement of a tube in the direction of its axis without exposing any live part, or disconnecting the lamp mechanically or electrically.

Other objects of the invention and advantages to be gained -by the use thereof, including its compliance with proposed or existing electrical codes, will be more apparent from the description of a preferred embodiment of the invention, and a modification thereof, which follows hereinafter having reference to the accompanying drawings, whereof:

Fig. 1 represents a side elevation of one end portion of an electric discharge tube with a terminal fitting and a base for supporting the fitting and carrying current thereto, such elements being constructed and assembled in accordance with my invention:

Figs. 2, 3 and 9 represent vertical cross sections of the same, taken respectively as indicated by the arrows II-II, IIIIII and IX-IX of Fig. 1;

Fig, 4 represents a longitudinal section of the same taken as generally indicated by the arrows IV-IV of Fig. 2, but showing portions of certain elements in side elevation;

Fig. 5 represents an exploded perspective view showing the two halves of the terminal fitting;

Fig. 6 is a view taken similarly to Fig. 1, but showing a modified form of tube, terminal fitting 13 Claims. (Cl. 176-122) and base, certain parts being broken away for clearness of illustration;

Fig. '7 is a P rspective view of the terminal fitting shown in Fig. 6;

Fig. 8 is a perspective view of the link which connects the base and terminal fitting shown in Fig. 6; and

Fig. 10 is an enlarged perspective view of one end of a prong of said link.

Inthe embodimentoi the invention illustrated in Figs. 1 to 5 and 9 of the drawings the end portion of electric discharge tube of conventional form is represented at i. Within the tube is an electrode 2 which Joins a conducting wire 3. The electrode 2 may be either a coil filament as illustrated or a conventional shell type electrode. Aillxed to the end of the tube I in surrounding relation to it is a terminal fitting 4 having a cylindrical bore 5 within which the tube is snugly fitted and secured. The terminal fitting is also provided with a socket 6 which parallels the bore 5. In its preferred form the socket 6 is of square or rectangular cross section. Near the inner end of the socket 6 a contact member 1, which may take the form of a metallic plate, is provided. The contact member 1 joins the conducting wire 3.

A desirable method of assembling the tube i and its terminal fitting 4 is to make the terminal fitting of two counterpart sections, as most clearly illustrated in Fig. 5, which are cemented or otherwise joined together at their meeting faces I. The terminal fitting may be made of glass, porcelain or other material having suitable insulating properties with the conducting wire 3 embedded between the two sections at their meeting faces. At the top of the terminal fitting 4 a keyway 9 is formed which is adapted to engage a key N in the base l2 upon which the lamp is supported. By thus keying together the tube l and its base I! allowance is made for substantial relative movement between these elements in the direction of the axis of the tube and at the same time lateral displacement of one such element with respect to the other is prevented.

In the drawings only a portion of the base I2 is shown. It may be assumed that where a number of tubes i are connected together in series, at the ends of the line of tubes thus connected base members l2 would be employed which would have a single socket l3, and that at intermediate points in the line base members would be employed having two such sockets i3. Such intermediate base members would include a second half at the left hand as viewed in Fig. 1, which would be in all respects similar to the right hand portion shown in the drawings except that the socket would extend in the opposite direction whereby the series oi tubes would be maintained in a straight line. The socket I3 is preferably oi square or rectangular cross section and, like the socket 4, has near its inner end a contact member i4 joined to a conducting wire it. The base members l2 may be secured to a ceiling, such as represented at II, or to any other structure upon which it -may be desired to mount a tube, by means oi flanges l1 and screws i8. Conveniently the base member I2 is also made of two counterpart sections oi insulating material joined together at their meeting iaces l3 and with the conducting wire I! embedded between the two sections. Obviously the keyway I and key ll may be reversed as between the terminal fitting 4 and base l2. or these elements may be engaged in sliding contact with capacity for limited relative movement by other means than that represented in the drawings.

A link electrically connects and mechanically supports the terminal fitting 4 or the tube l in relation to the base i2. In its preferred i'orm the link 20 has two prongs 2i, 22 oi square cross section designed to fit within the sockets i3 and 26, respectively. A conducting wire 23 is embedded within the link 20 and exposed only near the ends oi its prongs 2i 22. When the prongs, 22 are iully inserted within the sockets l3 and O, the ends oi the conducting wire 23 engage the contact members l4 and I completing the electrical circuit between the source of current supply and the tube or tubes to be energized. The ends oi the wire 23 make positive engagement with members l4 and I by means of resilient contact members 30 and II, biased toward the center line oi the link.

In its preferred form the link 20 is iormed with a ring 24 which serves as a convenient finger hold whereby the link may be readily inserted within or withdrawn from the sockets 6 and i3. Desirably the link 2ll-is attached to the base I2 by means oi a chain 32 to prevent its complete detachment therefrom. The chain 32 is oi such length that when the link 20 is withdrawn to the limit oi the chain, the link is completely withdrawn from the socket 6, but not completely withdrawn irom the socket l3, so that the lamp i may be removed without dislodgingthe link from its association with the base l2.

The base l2, as shown most clearly in Fig. 9, is provided with a cavity 33 having therein a vertically movable detent 34 urged downwardly by a spring 36. At its downward limit oi movement the shoulder 31 oi the detent 34 blocks the socket l3 and the lower end 38 projects downwardly from the base i2. when the fitting 4 is brought into engagement with the base I2, as illustrated in Fig. 9, the ietent 34 is forced upwardly against the spring 38, unblocking the socket l3 to permit access of the prong 2| oi the link 20. With the fitting 4 removed, the link 20 when withdrawn to the limit oi its movement as permitted by the chain 32 can be reinserted only as far as the detent which is located sumciently remote from the live contact member l4 to prevent arcing the wire 23. In this position the exposed contact member 3| oi prong 22 cannot become energized. It will be observed that the sockets 8 and I3 are relatively deep and too narrow for insertion oi a finger so that there is no occasion or possibility, with any normal use oi the device oi my invention, ior the person installing or removing a lamp to receive an electric shock.

In the modified iorm oi the invention illustrated in Fig. 8 oi the drawings, wherein all parts which remain unchanged are given the same reierence numerals as above, the tube la. its terminal fitting 4a, and the base l2a for supporting it are all rightangular in shape. This arrangement has an advantage in that a number oi lamps may be serially arranged in juxtaposed relation without any appreciable intervening gap between each lamp, thus providing continuous illumination across a ceiling. In this iorm oi the invention'th'e terminal fitting 4a includes an end portion 2i which caps the extremity oi the tube is and spaced annular portions 28 which surround the body oi the tube is to engage and support the same. In its intermediate areas the terminal fitting 4a is cut away, thus permittingmaximum illumination at the ends of the tubes and preventing overheating thereof. The base member l2a is iormed to complement the shape oi the terminal fitting 4a and to allow two tubes la. to be mounted in proximate relation. As in the case oi the first iorm oi the invention the conducting wires 30. and. Ila are wholly insulated and unexposed except near the inner ends oi the sockets 8a and Na.

The link 20a, as shown clearly in Fig. 8, is similar to link 20 except that its lower prong 22a is slotted, as indicated at 21, to surround a contact member la within the socket 8a and thus iorm an electrical connection with a terminal oi the conductor 23a. disposed within the slot 21. The upper prong 2la oi link 2011 is provided with a contact member 30a, as represented in Fig. 10, which is biased toward the center line oi the link, but when inserted within the socket He is flattened by its engagement with the lower wall thereoi. The contact member la is recessed in the slot 21 to a depth which is so related to the voltage oi the circuit that there is no possibility oi fiashover to anything external to or at the mouth oi the slot 21. In this modification there is thereiore no need for the detent 34, as the wire 23a may be energized without creating an electrical shock hazard.

It will be noted that both iorms oi my invention are characterized by their compactness, the provision for end play between the lamp and the base member which supports it, and the capacity for the tube to be quickly installed or released. The single moving part consists oi a link which can be readily grasped and which as soon as it is partially removed irom the sockets within which it is accommodated oiiers no opportunity ior contact with any live part. By virtue oi the shape oi its prongs the link assists the keyand keyway in resisting lateral displacement as between the tube and its supporting base,' while permitting relative movement in the longitudinal direction oi the tube.

The permissible endwise movement oi the tube relative to the base members is substantial in the sense that it is oi the order oi one-half inch or more. Such allowance for endwise movement without interrupting the electrical connection between the tube and base member is considerably greater than the permissible movements involved in other iorms of safety terminals, It avoids the necessity oi providing a rigid spacing member or channel running for the length oi the tube.

Although I have shown and described herein two specific embodiments oi my invention it. will be readily apparent that various changes maybe made in the iorm oi the lamp, its terminal fitting, the base for supporting the lamp and the key for connecting and assembling these elements;

and that, certain ieatures oi the invention may be used to advantage without the use of other features; all without departing from the spirit of the invention as defined in the annexed claims.

Having thus described my invention, I claim:

1. In combination, an electric discharge tube,

a base, and a link for electrically connecting and mechanically supporting said tube in relation to said base, said tube and said base each having therein a socket and a conductor with a portion exposed within said socket and otherwise insulated, said sockets being relatively deep and narrow whereby the exposed portions of the conductors are inaccessible to human fingers, and said link having prongs adapted to fit within said sockets and having a conductor embedded within the link and exposed only at areas where said prongs contact the conductors of said tube and base.

' 2. In combination, an electric dlschargetube having a terminal fitting at an end thereof, a base, and a link for electrically connecting and mechanically supporting said terminal fitting in relation to said base, said terminal fitting and base each having therein a socket and a conductor exposed within said socket and otherwise wholly embedded within the fitting or base. said sockets being relatively deep and narrow whereby the exposed portions of the conductors are inaccessible to human fingers. and said link having prongs adapted to fit within said sockets and having a conductor embedded within the link and exposed only at areas where said prongs contact the conductors of said fitting and base.

3. The invention set forth in claim 1 in which the link is further characterized by a finger hold in the form of a ring and the prongs are formed integrally with said ring.

4. The invention set forth in claim 1 in which the sockets and the prongs fitting therein are polygonal in cross section.

5. The invention set forth in claim 1 in which means are provided for preventing detachment of the link from the base.

6. The invention set forth in claim 1 in which means are provided for limiting outward movement of the link from the socket of the base to prevent its complete withdrawal from said socket.

'7. The invention set forth in claim 1 in which means are provided for blocking the socket of the base whereby, when the link ispartially withdrawn from said socket, said blocking means prevent its reinsertion to establish contact with the conductor leading to said socket, said blocking means including an element adapted to be engaged by the tube and rendering the blocking means inoperative when such engagement occurs.

8. The invention set forth in claim 1 in which the link has a prong which is interiorly recessed at its end, with a contact member housed within said recessed end, and the socket accommodating said prong has a companion contact member adapted to enter the recessed end of the prong.

9. The invention set forth in claim 2 in which the terminal fitting and base are each made of a plurality of sections of insulated material joined together. with their conductors embedded in the meeting faces of the Joined sections.

10. The invention set forth in claim 2 in which the terminal. fitting has 'a cylindrical bore accommodating an end of the tube, said bore paralleling the link-receiving socket of said fitting.

11. The invention set forth in claim 2 in which the base and terminal fitting have means to prevent lateral displacement, while permitting substantial relative endwise movement between said elements.

I 12. The invention set forth in claim 2 in which the end of the tube, its terminal fitting and the base for supporting it are all right-angular.

13. The invention set forth in claim 2 in which the end of the tube and its terminal fitting are right angular, the fitting capping the extremity of the tube and engaging the body thereof in surrounding relation and being cut away in the intermediate areas.

GEORGE E. BHOEMAKER.

No references cited. 

